The cytoplasm of a cell is the gel-like substance that fills the cell membrane, surrounding the nucleus and organelles. It is composed mainly of water, salts, and organic molecules. Cytoplasm serves as the site for many metabolic processes, facilitating the movement of substances within the cell and providing a medium for cellular components to interact. This includes processes such as protein synthesis and cellular respiration. Overall, the cytoplasm is vital for maintaining cell structure and function.